Sandikli basin located in the Inner West Anatolian part of the Aegean and it the basin open to the Buyuk Menderes basin. The basin is formed a combination of Kurucay and Kucuk Sincanli plains which is covers an area of approximately 1556 km(2) and also, the basin is semi-closed. According to lithological properties of geological units in the basin, the most important aquifers are alluvial and Hamamcay formation. In addition, locally groundwater is abstracted from the limestone levels in the base of the alluvium. Groundwater dynamic is described seasonal changes and movement of groundwater in the aquifer media. In order to clarify the dynamic of the groundwater in the region, groundwater level measurements have been made periodically 7 periods between 2007 to 2010 years and seasonal variations were investigated. In general, the groundwater level in the Kurucay basin changed from 3.29 to 75.18 m in wet period; from 4.38 to 83.65 m in dry period respectively. The groundwater level in the Kucuk Sincanli plain measured between 0.75 and 4.48 m in wet period, 1.09 and 4.85 m dry period, respectively. Groundwater flow direction is toward to northeast direction in south of the basin and to north in the west of the basin. It is also toward to the Karadirek creek in south within the Kucuk Sincanli plain. In the basin, average groundwater level decrease is 10 m. It also decreases to 25 m in Kusura and Emirhisar regions. In addition, decreasing to the limestone aquifer observed in these regions. The reasons of the excessive decrease in groundwater level are withdrawing of water from wells at over assignment and decreasing of rainfall and snowfall in recent years.